Disable legacy 'harmony' option from uglifier_args (#20178)

* Disable legacy 'harmony' option from uglifier_args

Fixes EDUENG-112

This patch eliminates the deprecated Uglifier warnings and improves
build performance without affecting functionality.

* Back out changes in API & tutorials docs

They were breaking the build for those targets, and I can't test them
locally.

Author: rmloveland

src/current/_config_base.yml

@@ -58,8 +58,6 @@ jekyll-minifier:
   remove_style_attributes: 'false'
   simple_boolean_attributes: 'false'
   simple_doctype: 'false'
-  uglifier_args:
-    harmony: 'true'
 jekyll_get_json:
 - data: cloud_api_releases
   json: https://cockroachlabs.cloud/assets/docs/api/manifest.json